Ok, so people feel there are issues with running PWM on Low z injectors, and i am aware of this. From what I have researched is that the OEM use Peak and Hold, so i thought, how can i do this? Low and behold, i found something on Megsquirt forum by another Mini enthusiast, infact its the same chap i mentioned in one of my other topics on dual table firmware and siamese port injection, Jean Belanger. He has designed and built an add on board for the Megasquirt to convert its lowley two injector outputs to P&H.
http://www.jbperf.com/p&h_board/index.htmlOk,
Any one smart enough to help me work out how I can mod the GenBoard V3 to wire this in to four of my eight injector outputs. I know for a fact that I wont ever be using all eight drivers at once, I have the two DPAK FET drivers installed for extra outputs. I was thinking of maybe INJ drivers 4,5,6,7 converted to P&H, either using this board hard wired internaly (pakaging could be difficult) or building the board into an external unit. I realise that he FETs onboard need to come off which ever, and the rewire the gate. The bit i am really confused with is the FET driver circuit. I have had a look at the GenBoard schematic, but, i dont understand it one bit, its not like what i had expected, maybe Simplified?? i just cant follow it logicaly. Looks to me as if the add on board uses the raw injector signal from the processor??
It cant be that complicated can it to get this to work, can it?
And before anyone says just use a resistor in series with the injector, I am, I want to bin it, as I know for a fact that the injector characteristics have drasticaly changed!! so much so that the injector thats installed was the one when used on the OEM ECu, flat lined and went lean at full throttle. Ramp up times are huge with maybe slower ramp closed, even with transient diode, dont forget High z ingectors resistance is the injector coil where as Low Z and resistor, more than half the resistance is the resistor, it must play some part in the equasion of things, and i think it is this thats 'increasing' the physical flow rate of the injector. I recon i could get away with using the original injector that was fitted to the car which would originaly max out at around 80bhp. Dont get me wrong, the resistor works a treat, its just not what i want. I now have the engine running well enough to start experimenting, i just dont want to smoke the ECU.
This could be an interesting project
